Dental implants are well known in the art and typically include a dental anchor securely inserted into the patient's jawbone, and an abutment member mountable to the dental anchor, the abutment utilized for coupling a restoration.
One of the initial steps in the implantation process and perhaps the most crucial step is determining where to place the implant anchor within the jawbone over the edentulous area. This first initial step is crucial in that it determines the quality of the implantation process and the likelihood of success. Therefore the initial determination of where to drill, at what angle, depth, size, greatly impacts the success of the implantation process. It is extremely important that the hole drilled in the bone tissue has a correct location and inclination with respect to the thickness and morphology of the bone. Care is to be taken to avoid any imperfect fit of the implant, and, most critically, to avoid any perforation or damage to nearby anatomical structures.
In order to facilitate the proper placement, direction, and depth of the drilling process practitioners plan the procedure. In so doing practitioners rely on medical imagery such as X-rays, and computer tomography scans (CT scans) to carefully planned the procedure. The planned procedure generally includes determining the drill sequence, drill location, size and depth. In order to facilitate this process and in order to ensure that the procedure is carried out according to plan, a drill guide has been developed that provides a practitioner with the tool to minimize errors.
A dental drill guide is an acrylic resin mask obtained from a model of the patient's dental arch, adapted to exactly fit over the patient's teeth and/or edentulous areas of the jaw (or just “over the patient's jaw”). The guide mask is provided with one or more guiding holes that are placed in the exact position of the holes to be made or, more preferably, it is provided with one or more metallic hollow cylinders plunged in the resin in the desired location.
Determining the position of the metallic hollow cylinder, also referred to as a stent or a tubular sleeve, is a central and key factor in determining the quality of the drill guide. In planning the implantation procedure, particularly with the aid of modern medical imagery prior to the CAD/CAM production of the drill guide, a clinician can plan the best suited position of the sleeve relative to the medical imagery available.
While this determination is done on the basis of the clinician's knowledge and practice and aided with medical imagery, however, the drill guide itself is generally prepared by a technician and not by the implanting practitioner, therefore lending itself to human error.
More over inherent errors in the medical imagery devices, giving an error of about 10%, leads to further error in determining the location of the sleeve within the drill guide. However such errors are usually not identified until the onset of the implant procedure, itself where a mismatch between the drill guide and the clinical situation before an implanting practitioner is realized.
Most drill guides are limited in that once the template is made its configuration cannot be further adjusted.
Some drill guides provide the option of correcting the sleeve location within the drill guide, as for example the drill guides taught by U.S. Pat. No. 7,905,726 to Stumpel, and Canadian Patent Publication No. 2,484,475 to Csillag. However both Stumpel and Csillag are limited in the range of motion they offer over the edentulous area, specifically they do not provide a full range of motion over the edentulous area. Stumpel and Csillag only provide the opportunity to make incremental changes to the drill guide sleeve rather than allowing a full range and changes to be made to the guide.